So like it lives on your device at some ip:port within your browser? I ran sillytavern, that's my only concept of something like that
sometimes you can even get away with file://.../index.html, pointing it at the local output, but not all web apps work that way due to cross-site permission issues so usually you'd run a local web server and host it from there, either on the same machine or within your LAN the javascript build systems usually have a webserver built in for developer use; eg "pnpm run dev" will spin up its own webserver locally (see https://github.com/hzrd149/nostrudel?tab=readme-ov-file#running-locally)